RU2149213C1 - Wear-resistant steel - Google Patents

Abstract

FIELD: metallurgy, particularly, high-manganese cast steels used in manufacture of mining equipment operating under conditions of extreme north and heavy impact and abrasive loads. SUBSTANCE: steel contains components in the following ratio, wt.%: carbon, 0.95-1.10; silicon, 0.10-0.49; manganese, 13.0-14.5; chromium, 0.30-0.80; nickel, 0.20-0.50; titanium, 0.01-0.05; aluminum, 0.020-0.050; calcium, 0.005-0.040; cerium, 0.010-0.040; phosphorus, 0.01-0.06; iron, the balance. The steel possesses high wear hardening without crack formation and high cyclic resistance to heavy impact-abrasive loads. EFFECT: higher efficiency. 1 tbl

Description

 The invention relates to metallurgy of steels, namely to high manganese casting steels used for the manufacture of structures of mining equipment operating in the Far North under the influence of strong shock-abrasive loads.

Known wear-resistant steel grade 110G13L (GOST 2176), containing the following components, wt.%:
carbon - 0.9 - 1.40
silicon - 0.80 - 1.00
Manganese - 11.50 - 15.0
chromium - not more than 1.00
nickel - no more than 1,70
copper - no more than 0.30
sulfur - not more than 0.05
phosphorus - not more than 0.12
iron - the rest
The disadvantage of this steel is that this steel does not have a sufficiently high level of operational properties in conditions of strong shock-abrasive loads.

The steel (SU N 1659519 A1) used in excavation is widely known, containing the following components, wt.%:
carbon - 0.90 - 1.4
silicon - 0.50 - 1.0
Manganese - 11.5 - 14.0
nickel - 0.10 - 2.00
copper - 0.70 - 2.0
calcium - 0.05 - 1.0
tungsten - 0.4 - 0.8
titanium - 0.03 - 0.04
iron - the rest
This steel with a cross section of up to 250 mm has ambiguous riveting under strong shock-abrasive loads and, as a consequence, insufficient wear resistance, and the presence of a high calcium content in steel makes it non-technological when pouring molds due to the tightening of the cup during casting.

The prototype is steel (SU 1317033 A1) containing the following components, wt.%:
carbon - 1.0 - 1.4
silicon - 0.50 - 1.0
Manganese - 11.0 - 14.0
titanium - 0.2 - 0.8
zirconium - 0.1 - 0.4
nitrogen - 0.1 -0.4
rare earth metals - 0.05 - 0.20
calcium - 0.08 - 0.35
iron - the rest
This steel has improved mechanical properties at constant loads and increased crack resistance during casting. However, under strong shock-abrasive loading, it has a lower hardenability without cracking and a lower cyclic resistance, which is a consequence of excessive alloying with rare-earth metals, as well as a high content of titanium carbonitrides with a high stress concentration coefficient around them.

 The basis of the present invention was the task of developing a composition of wear-resistant steel with high riveting without cracking and high cyclic resistance under strong shock-abrasive loading.

The problem is solved in that in wear-resistant steel containing carbon, silicon, manganese, titanium, calcium and rare-earth metals, it is new that it contains cerium as a rare-earth metal and also additionally contains nickel, chromium, aluminum and phosphorus in the following the ratio of components, wt.%:
carbon - 0.95 - 1.10
silicon - 0.10 - 0.49
Manganese - 13.0 - 14.5
chrome - 0.30 - 0.80
nickel - 0.20 - 0.50
titanium - 0.01 - 0.05
aluminum - 0,020 - 0,050
calcium - 0.005 - 0.040
cerium - 0.010 - 0.040
phosphorus - 0.01 - 0.06
iron - the rest
The introduction of carbon in an amount of 0.95% is selected from the need to ensure austenitic steel. The upper limit of carbon of 1.10% is adopted to ensure the absence of carbide precipitation along the boundaries of austenitic grain.

 A lower limit of silicon content of 0.10% is adopted to ensure deoxidation. An increase in silicon content to 0.49% provides a fairly high level of strength properties, helps to mitigate zonal and grain-limited segregation (including carbon), which increases the stability of austenite.

 Quantitatively, 13.0% manganese is selected from the need to provide the required austeniticity of the steel and obtain the required level of riveting. The maximum manganese content of 14.5% is selected from environmental conditions.

 Chrome in combination with manganese increases the stability of austenite, this limits its maximum content in steel 0.80%. The minimum chromium content of 0.30% is selected to provide the necessary structural components that provide a high level of steel ripening.

 Nickel as an alloying element increases resistance to brittle fracture, increases ductility and viscosity, reduces sensitivity to stress concentrators and lowers the temperature of cold brittleness threshold, and also increases the stability of austenite, which increases in the presence of chromium. The minimum amount of nickel of 0.20% provides steel lowering the cold brittleness threshold, and the maximum amount of 0.50% increases the endurance limit.

 The introduction of aluminum in an amount of 0.020% improves the deoxidation of steel. The content in the steel of aluminum in an amount of 0.050% provides sufficient resistance of the steel against the growth of austenitic grain.

 Cerium in combination with calcium provides the formation of globular non-metallic inclusions in steel, therefore their content is limited to 0.01 - 0.04% and 0.005 - 0.040%, respectively. Such a content of cerium and calcium does not make steel non-technological during casting and increase the fluidity of steel.

 The maximum phosphorus content of 0.06% was selected from the conditions of increasing the fluidity of steel and the absence of the formation of carbon-phosphide eutectic, which reduces the crack resistance of steel.

 Titanium in an amount of 0.01 - 0.05% is introduced into steel as a modifier in order to obtain a fine-grained structure.

 To obtain the steel of the proposed composition, experimental melts were conducted on the six chemical compositions indicated in the table, including prototype steel. Steel was smelted in an induction furnace.

 When smelting, ferroalloys of the following grades were used: ferrosilicon grade FS-45, manganese metal, ferrochrome markim FKh050A, nickel, ferrotitanium grade FT and 40A, calcium, aluminum and cerium.

 Silicon and manganese ferroalloys were used in crushed form with a fraction of 5-50 mm.

 Steel was poured into sand forms of 50 kg.

The ability of steel to strain hardening (hardening) was determined on special samples that underwent heat treatment — austenitization at 1050 ^° C with cooling in water by repeatedly pressing a carbide ball until the first crack appeared.

 The chemical composition and properties of the proposed and known steels are given in the table.

 As follows from the table, the proposed steel is superior to known for riveting under intense impact loading. A melting containing alloying elements below the lower limit of alloying has a fairly high riveting due to underdevelopment and low stability of austenite.

 Melting, melted in chemical composition exceeding the upper limit of alloying, has identical riveting, as well as known, due to the release of carbon phosphides along the grain boundaries.

 The technical and economic effect of the use of the inventive steel is expressed in increasing the durability of equipment operating in conditions of intense shock-abrasive wear.

Claims (1)

Wear-resistant steel containing carbon, silicon, manganese, titanium, calcium and rare-earth metals, characterized in that it contains cerium as a rare-earth metal and also additionally contains nickel, chromium, aluminum and phosphorus in the following ratio, wt.%:
Carbon - 0.95 - 1.10
Silicon - 0.10 - 0.49
Manganese - 13.0 - 14.5
Chrome - 0.30 - 0.80
Nickel - 0.20 - 0.50
Titanium - 0.01 - 0.05
Aluminum - 0.020 - 0.050
Calcium - 0.005 - 0.040
Cerium - 0.010 - 0.040
Phosphorus - 0.01 - 0.06
Iron - Else

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